All aboard Labor's Metronet express

THE West Australian Labor Party has revealed the next stop on its ambitious rail plan for Perth, promising a rail line to the growing suburb of Ellenbrook at a cost of $863.5 million.

The cornerstone of the Labor election campaign, the Metronet rail project is designed to link Perth's growing suburban fringe while freeing up congestion in the city.

Wednesday's Ellenbrook rail promise from Labor leader Mark McGowan was an opportunity for another shot at Premier Colin Barnett, who has been criticised for failing to uphold a promise made at the 2008 state election that the Liberals would build a rail line to the suburb north-east of Perth.

Mr McGowan said the 21km line would cost $863.5 million - excluding rail cars - and construction was expected to start during 2014/15.